This invention provides a semiconductor device such as an MOS transistor and a method of fabricating the same wherein a field oxide film is provided to surround a device region of a semiconductor substrate (including well), providing a gate on the device region via a gate insulating film, forming main doped layers destined to become a source and a drain in the device region of the semiconductor substrate between the gate and the field oxide film on opposite sides of the gate, and providing main active layers (high-concentration diffusion layers) having the impurity diffused and activated therein. Sub-doped layers are formed by selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film (except in the vicinity of the gate) and sub-active layers having the impurity diffused and activated therein are provided.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of fabricating a semiconductor device comprising: a step of forming a field oxide film having a bird's beak at an inner peripheral portion to surround a device region of a semiconductor substrate, a step of forming a gate insulating film on a surface of the semiconductor substrate within the device region, a step of forming a gate on the gate insulating film, a step of forming main doped layers by adding to regions of the semiconductor substrate between the gate and the field oxide film impurity for forming a source and a drain, a step of forming sub-doped layers by selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film, and a step of forming main active layers constituting the source and the drain and forming sub-active layers so as to cover an overlap between the bird's beak of the field oxide film and the main active layers by, after forming the whole surface of the semiconductor substrate with an insulating film, effecting annealing to activate the main doped layers and activate the sub-doped layers.
2. A method of fabricating a semiconductor device according to claim 1, further comprising a step of forming a mask oxide film on a surface of the gate between the step of forming the gate and the step of forming the main doped layers.
3. A method of fabricating a semiconductor device according to claim 1, wherein short-period annealing using a lamp annealer is effected in the step of forming the main active layers and the sub-active layers.
4. A method of fabricating a semiconductor device according to claim 2, wherein short-period annealing using a lamp annealer is effected in the step of forming the main active layers and the sub-active layers.
5. A method of fabricating a semiconductor device according to claim 1, wherein impurity is selectively added to the semiconductor substrate by penetration through the field oxide film at a peripheral portion of the device region in the step of forming the sub-doped layers.
6. A method of fabricating a semiconductor device according to claim 2, wherein impurity is selectively added to the semiconductor substrate by penetration through the field oxide film at a peripheral portion of the device region in the step of forming the sub-doped layers.
7. A method of fabricating a semiconductor device according to claim 3, wherein impurity is selectively added to the semiconductor substrate by penetration through the field oxide film at a peripheral portion of the device region in the step of forming the sub-doped layers.
8. A method of fabricating a semiconductor device according to claim 4, wherein impurity is selectively added to the semiconductor substrate by penetration through the field oxide film at a peripheral portion of the device region in the step of forming the sub-doped layers.
9. A method of fabricating a semiconductor device comprising: a step of forming a pad oxide film on a semiconductor substrate, a step of forming a silicon nitride film on the pad oxide film at a device region of the semiconductor substrate, a step of forming a field oxide film having a bird's beak at an inner peripheral portion to surround the device region using the silicon nitride film as an oxidation preventing film, a step of forming sub-doped layers by, after removing the silicon nitride film, selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film, a step of forming a gate insulating film and simultaneously activating the sub-doped layers to form sub-active layers so as to cover an overlap between the device region and the bird's beak of the field oxide film by effecting thermal oxidation on the device region of the semiconductor substrate, a step of forming a gate on the gate insulating film, a step of forming main doped layers by adding to regions extending to the sub-active layers of the semiconductor substrate between the gate and the field oxide film impurity for forming a source and a drain, and a step of forming main active layers constituting the source and the drain by, after forming the whole surface of the semiconductor substrate with an insulating film, effecting annealing to activate the main doped layers.
10. A method of fabricating a semiconductor device comprising: a step of forming a pad oxide film on a semiconductor substrate, a step of forming a silicon nitride film on the pad oxide film at a device region of the semiconductor substrate, a step of forming a field oxide film having a bird's beak at an inner peripheral portion to surround the device region using the silicon nitride film as an oxidation preventing film, a step of forming a white ribbon oxide film after removing the silicon nitride film and the pad oxide film, a step of forming sub-doped layers by selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film, a step of forming a gate insulating film and simultaneously activating the sub-doped layers to form sub-active layers so as to cover an overlap between the device region and the bird's beak of the field oxide film by, after removing the white ribbon oxide film, effecting thermal oxidation on the device region of the semiconductor substrate, a step of forming a gate on the gate insulating film, a step of forming main doped layers by adding to regions extending to the sub-active layers of the semiconductor substrate between the gate and the field oxide film impurity for forming a source and a drain, and a step of forming main active layers constituting the source and the drain by, after forming the whole surface of the semiconductor substrate with an insulating film, effecting annealing to activate the main doped layers.
11. A method of fabricating a semiconductor device comprising: a step of forming a field oxide film having a bird's beak at an inner peripheral portion to surround a device region of a semiconductor substrate, a step of forming a gate on the device region of the semiconductor substrate via an intervening gate insulating film, a step of forming sub-doped layers by selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film, a step of forming a mask oxide film on a surface of the gate and simultaneously activating the sub-doped layers to form sub-active layers so as to cover an overlap between the device region and the bird's beak of the field oxide film by effecting thermal oxidation, a step of forming main doped layers by adding to regions extending to the sub-active layers of the semiconductor substrate between the gate and the field oxide film impurity for forming a source and a drain, and a step of forming main active layers constituting the source and the drain by, after forming the whole surface of the semiconductor substrate with an insulating film, effecting annealing to activate the main doped layers.
12. A method of fabricating a semiconductor device comprising: a step of forming a field oxide film having a bird's beak at an inner peripheral portion to surround a device region of a semiconductor substrate, a step of forming a gate on the device region of the semiconductor substrate via an intervening gate insulating film, a step of forming a mask oxide film on a surface of the gate, a step of forming sub-doped layers by selectively adding impurity to regions of the semiconductor substrate at boundaries between the device region and the field oxide film, a step of forming sub-active layers so as to cover an overlap between the device region and the bird's beak of the field oxide film by effecting annealing in an inert atmosphere to activate the sub-doped layers, a step of forming main doped layers by adding to regions extending to the sub-active layers of the semiconductor substrate between the gate and the field oxide film impurity for forming a source and a drain, and a step of forming main active layers constituting the source and the drain by, after forming the whole surface of the semiconductor substrate with an insulating film, effecting annealing to activate the main doped layers.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 11, 1999
September 18, 2001
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.